Process for making alloys



' March 11, 1958 F. E. DRUMMOND 2,826,494

PROCESS FOR MAKING ALLOYS Filed Dec. 27, 1955 INVENTOR FOLSOM E. DRUMMOND mlmm. MW fllllllllllllllll ATTORNEYS hired States Patent PRGCESS FOR MAKING ALLOYS Folsom E. Drummond, Washington, D. 63., assignor to The Commonwealth Engineering Company or (lino, Dayton, Ohio, a corporation of Ohio Application December 27, 1955, Serial No. 555,473

8 Claims. (Cl. 75-122) This invention relates to the treatment of molten metals with gaseous substances, and more particularly to a process of producing alloy metals, especially alloy steels, wherein at least one of the alloying metal constituents is introduced into the molten metal in the form of a gaseous heat-decomposable compound.

One of the objects of this invention is to produce alloy metals directly and quickly by blowing metal in the form of a gaseous heat-decomposable metal compound into a molten metal mass.

Another object of the invention is to provide an improved process and apparatus for making alloy steels, similarly as in the Bessemer process, and wherein the desired metal or metals are introduced as gaseous metal carbonyls.

Another object of the invention is to provide a process for producing alloy metals which contain appreciable amounts of at least one of the metals of the group consisting of nickel, chromium, molybdenum, vanadium, tungsten, cobalt, columbium, manganese, titanium,

tantalum, aluminum, silicon, Zirconium, and the like, and

wherein such metals are introduced in the form of their gaseous decomposable metal compounds.

Still another object of the invention is to provide a method for manufacturing low carbon and steel alloys, particularly those alloys containing chromium, nickel, molybdenum, cobalt, and tungsten, and wherein these alloy metals are introduced into the molten metal bath of steel as their carbonyls.

These and other objects and advantages will become apparent as the invention is more fully disclosed and as hereinafter taken in conjunction with the drawings where- Figure 1 is a diagrammatic view, partly in section, and illustrating a furnace for holding molten metal and introducing the alloy metal as a gaseous metal heat-decomposable compound.

Figure 2 is a view illustrating a cupola which is tiltable, similarly as in Bessemer type furnaces, and which is mounted on trunnions, and illustrating by a section broken away the porous false bottom construction of the furnace.

In accordance with the present invention, and referring more particularly to the drawings, a furnace as illustrated in Figure 1 at It), fabricated of refractory material and insulated as at 11, is provided with an opening 12 in the bottom, which is adapted to be connected through a pipe 13 by branch lines 14, 15 and 16 with storage tanks 17, 13 and 19 respectively. In tanks 17, 18 and 19 are stored the heat-decomposable metal compound. Metals to be introduced into the molten metal are in the form of gaseous metal compounds, e. g. carbonyls, hydrides, nitrides, or the like. Carbonyls of metals such as nickel, chromium, tungsten, molybdenum, iron, etc., which are commercially available may be employed. The metal compound may either be stored in liquid or gas form, depending upon the compound used. When liquid, it is 2,826,494 Patented Mar. 11, 1953 2 transformed into the gaseous metal compound as by the application of heat and lowering the pressure to volatilize the same which flows through line 13 to the water cooled tuyere 20 and into the molten metal as at 21.

By introducing the metal as a gaseous carbonyl the same can be readily dispersed through the molten metal bath and the metals more intimately united than when employing conventional scrap-addition methods. The process also effects greater economy of materials and time in preparing the alloys since the addition metals are in fluid form and dilfuse through the molten metal in a matter of seconds. The metal carbonyl gas decomposes releasing the metal and waste carbon monoxide gas which passes off and is burned at the mouth of the cupola or furnace 10.

When the desired amount of metal has been introduced as shown by chemical analysis, the flow of gaseous metal compound to the molten mass is cut oil, as by closing the valve 22 at the base of the furnace, and the molten mass is further treated as desired to form the finished alloy metal.

In the modification shown in Figure 2, a furnace is mounted on trunnions 31 similarly as in a Bessemer converter. A false bottom 32 is provided having perforations 33 for the entry of air and heat-decomposable gaseous metal compound. Air is admitted in the lower chamber 34 through the pipe line 35 and metal carbonyls or the like heat-decomposable metal compounds, are introduced at the bottom of the furnace through line 36 and fluid coated tuyere 3'7.

In operation, for example in making alloy steels, a batch of molten metal, such as shown at 38, is placed in the cupola and, after first blowing air therethrough to reduce the carbon content and phosphorus as well as silicon, the alloy metal in the form of a heat-decomposable gaseous metal compound is then forced therein through line 36. After blowing the air through the molten mass and adding the required amount of gaseous metal carbonyl, the batch is then preferably treated with deoxidizer such as form-manganese and speigeleisen (a low grade ferro-manganese) ferro-silicon, pig iron, as Well as aluminum (as desired), to produce a final alloy of the desired composition. The addition of deoxidizers eliminates most of the trapped gases, and corrects the composition to the desired content of carbon, silicon, manganese and alloying constituents. Aluminum is added to quiet the evolution of gases from the steel.

Thereafter the molten steel is poured from the converter into a teeming ladle, from thence to the ingot molds. The ingot is then removed and sent on through soaking pits and rolling mills, etc.

As a typical example of utilizing the process, stainless steels having a chromium content of 12 to 22% and nickel content of from 10 to 21% are produced by introducing the chromium and nickel into the molten steel mass as chromium hexacarbonyl and nickel carbonyl gaseous compounds.

Where molybdenum is to also be incorporated in the alloy steel the same is introduced into the molten metal batch as molybdenum hexacarbonyl. In this matter stainless steels having the desired content of chromium, nickel and molybdenum may be made by introducing the metals in the molten metal batch as heat-decomposable gaseous metal compounds. Copper likewise may be introduced as copper carbonyl.

Nickel steels containing 7.5% to 12% nickel, chromium from 0.02 to 6%, copper 0.05 to 2% and molybdenum 0.03 to 2% may be made by introducing these alloying constituents as heat-decomposable gaseous metal compounds. Such nickel steels generally would contain silicon in about 0.03 to 0.40%, manganese from 0.20 to 1.0%, and carbon from about 0.03 to 0.2%, the remainder being iron.

High tensile steels, such as used in making valves, and which contain from 18 to 24% chromium and 7 to 11% manganese may be produced by providing a molten mass of iron containing about 0.25% silicon, 0.08% to 0.5% carbon and 0.1% to 0.4% nitrogen, and then passing into the molten mass the requisite amount of alloying metals in the form of their gaseous metal carbonyls, the same being forced into the molten mass utilizing a converter as described.

The improvement feature or" this new process of making alloys of various compositions comprises the step of introducing the alloy metal into the molten metal batch as a heat-decomposable metal compound. in this manner the alloying metal is made to completely and rapidly diffuse through the molten metal mass whereby an alloy of more uniform characteristic properties is produced than would be possible by conventional methods.

From the foregoing description of the method of preparing alloys by the present invention, it is apparent that it is adapted to Wide use and application in the production of various alloys.

Further, While as a specific embodiment of the invention has been described for making alloy steels, it is manifest that'the method is applicable to the making of non-ferrous as Well as other type of alloys.

It is accordingly, contemplated that all such modificationsand adaptations of the present invention for making difierent alloys and the advantages thereof will now be apparent to those skilled in the art Without need of further description.

What is claimed is:

1. A method of making alloys which comprises establishing a mass of molten metal of the desired composition and introducing at least one alloying metal constituent therein as heat-decomposable gaseous metal 4 compounds, said gaseousmetal compounds consisting of metal carbonyls.

2. In the method of making alloy steels containing a chromium element, the step of introducing said chromium element as a heat-decomposable gaseous compound.

3. In the process of making stainless steel alloys which comprises the steps of introducing the alloy metal into a molten metal batch as a heat-decomposable metal compound, said metal compound being decomposed to release metal to form a stainless steel alloy.

4. In the process of making stainless steel alloys which comprises the steps of introducing the alloy metal into a molten metal batch as a heat-decomposable metal compound, said metal compound being decomposed to release metal to form a stainless steel alloy, and treating the resultant metal batch while in the molten state with deoxidizer to correct the composition and eliminate trapped gases therefrom.

5. An alloy of iron and chromium made in accordance with the method of claim 2.

6. A stainless steel made in accordance with the method of claim 3.

7. A stainless steel made in accordance with the method of claim 4.

8. A method of making stainless steels having a chromium content of 12 to 22% and nickel content of 10 to 21% which comprises the steps of establishing a mass of molten steel, and introducing said chromium and nickel into said molten steel mass as gaseous chromium hexacarbonyl and gaseous nickel carbonyl.

References Cited in the file of this patent UNITED STATES PATENTS 1,674,119 Miyaguchi June 19, 1928 1,786,393 Schwarzkoph Dec. 23, 1930 2,711,955 Jordan June 28, 1955 

3. IN THE PROCESS OF MAKING STAINLESS STEEL ALLOYS WHICH COMPRISES THE STEPS IN INTRODUCING THE ALLOY METAL INTO A MOLTEN METAL BATCH AS A HEAT-DECOMPOSABLE METAL COMPOUND, SAID METAL COMPOUND BEING DECOMPOSED TO RELEASE METAL TO FORM A STAINLESS STEEL ALLOY. 